Air conditioning system and control method therof

ABSTRACT

An air conditioning system and a control method thereof. The air conditioning system includes: a plurality of indoor units connected in parallel; a plurality of outdoor units connected in parallel; and a coolant circulation circuit which flows through each of the indoor units connected in parallel and each of the outdoor units connected in parallel respectively, and which exchanges heat with each of the indoor units and each of the outdoor units; wherein the air conditioning system further includes a controller which, based on an activation number of the indoor units, a total number of the indoor units and a total number of the outdoor units, defines an upper limit of an activation number of the outdoor units, so that the flow rate of the coolant flowing through the activated outdoor units is not lower than a preset flow rate.

FOREIGN PRIORITY

This application claims priority to Chinese Patent Application No.201910275837.X, filed Apr. 8, 2019, and all the benefits accruingtherefrom under 35 U.S.C. § 119, the contents of which in its entiretyare herein incorporated by reference.

FIELD OF THE INVENTION

The present disclosure relates to the field of air conditioning, and inparticular to an air conditioning system and a control method thereof.

BACKGROUND OF THE INVENTION

Currently, in large-scale scenarios with refrigeration requirements incommercial applications, a coolant (e.g., water) circulation circuit isusually disposed between indoor units and outdoor units to transfer coldor heat. A refrigerant circuit is also usually disposed in each outdoorunits, and the refrigerant therein exchanges heat with the coolantcirculation circuit through a heat exchanger (for example, a weldedplate heat exchanger) in the refrigerant circuit. In this case, in orderto prevent the heat exchanger from freezing due to insufficient heatabsorption, a threshold value should be set for the flow rate of thecoolant in the coolant circulation circuit flowing through each outdoorunits. When the flow rate is below the threshold value, an alarm istriggered. However, in practical applications, for example, when a totalload of the indoor units is low due to the small number of operatingindoor units, if a large load is still maintained on the outdoor unitand the adjustment capability of a bypass flow path is insufficient, theaforementioned alarm will also be triggered. Because such phenomena arecommon, alarm will be triggered frequently, or even the system will beshut down, which greatly affects the reliability of system operation anduser experience.

SUMMARY OF THE INVENTION

In view of this, an air conditioning system and a control method thereofare provided by the present disclosure, thereby effectively solving orat least alleviating one or more of the above problems in the prior artand in other aspects.

In order to achieve at least one object of the present disclosure, anair conditioning system is provided according to an aspect of thepresent disclosure, which includes: a plurality of indoor unitsconnected in parallel; a plurality of outdoor units connected inparallel; and a coolant circulation circuit which flows through each ofthe indoor units connected in parallel and each of the outdoor unitsconnected in parallel respectively, and which exchanges heat with eachof the indoor units and each of the outdoor units; wherein the airconditioning system further includes a controller which, based on anactivation number of the indoor units, a total number of the indoorunits and a total number of the outdoor units, defines an upper limit ofan activation number of the outdoor units, so that the flow rate of thecoolant flowing through the activated outdoor units is not lower than apreset flow rate.

Optionally, the upper limit of the activation number of the outdoorunits is N_(limit)=K*(M_(running)/M_(total))*N_(total); where K is a setcoefficient, M_(running) is the activation number of the indoor units,M_(total) is the total number of the indoor units, and N_(total) is thetotal number of the outdoor units.

Optionally, when the obtained N_(limit)≤1, the N_(limit) is determinedto be 1; and when the obtained N_(limit)>1, the N_(limit) is roundeddown.

Optionally, K≤1 or K>1.

Optionally, K=2.5.

Optionally, the preset flow rate is not lower than 70% of a rated flowrate of the outdoor units.

Optionally, the air conditioning system further includes a temperaturesensor disposed downstream of the indoor units in the coolantcirculation circuit to sense a temperature of returned water; whereinthe controller is further configured to, when the temperature ofreturned water is higher than a preset temperature, increase theactivation number of the outdoor units within the upper limit of theactivation number of the outdoor units, and/or increase the operatingfrequency of the activated outdoor units.

In order to achieve at least one object of the present disclosure, acontrol method of an air conditioning system is further providedaccording to another aspect of the present disclosure, wherein the airconditioning system includes: a plurality of indoor units connected inparallel; a plurality of outdoor units connected in parallel; a coolantcirculation circuit which flows through each of the indoor unitsconnected in parallel and each of the outdoor units connected inparallel respectively, and which exchanges heat with each of the indoorunits and each of the outdoor units; and a controller; the controlmethod includes: based on an activation number of the indoor units, atotal number of the indoor units and a total number of the outdoorunits, defining an upper limit of an activation number of the outdoorunits, so that the flow rate of the coolant flowing through theactivated outdoor units is not lower than a preset flow rate.

Optionally, the upper limit of the activation number of the outdoorunits is N_(limit)=K*(M_(running)/M_(total))*N_(total); where K is a setcoefficient, M_(running) is the activation number of the indoor units,M_(total) is the total number of the indoor units, and N_(total) is thetotal number of the outdoor units.

Optionally, when the obtained N_(limit)≤1, the N_(limit) is determinedto be 1; and when the obtained N_(limit)>1, the N_(limit) is roundeddown.

Optionally, K≤1 or K>1.

Optionally, K=2.5.

Optionally, the preset flow rate is not lower than 70% of a rated flowrate of the outdoor units.

Optionally, a temperature of returned water after the coolant in thecoolant circulation circuit flows out of the indoor units is obtained;when the temperature of returned water is higher than a presettemperature, the activation number of the outdoor units is increasedwithin the upper limit of the activation number of the outdoor units,and/or the operating frequency of the activated outdoor units isincreased.

According to the air conditioning system and the control method thereofof the present disclosure, by associating the operating state of theindoor units with the adjustment of the outdoor units, the system iscapable of defining an upper limit of the activation number of theoutdoor units based on an activation number of the indoor units, a totalnumber of the indoor units and a total number of the outdoor units, sothat the flow rate of the coolant flowing through the activated outdoorunits is not lower than a preset flow rate. In this way, it is ensuredthat the outdoor units will not be frozen due to overly low flow rateeven if the indoor units have a low load, and triggering of freezingalarm is also avoided.

BRIEF DESCRIPTION OF THE DRAWINGS

The technical solutions of the present disclosure will be furtherdescribed in detail below with reference to the accompanying drawingsand embodiments, but it should be understood that the drawings are onlyprovided for the purpose of explanation, and should not be considered aslimiting the scope of the present disclosure. In addition, unlessotherwise specified, the drawings are only intended to conceptuallyillustrate the structures and constructions described herein, and arenot necessarily drawn to scale.

FIG. 1 is a schematic diagram of an embodiment of an air conditioningsystem of the present disclosure.

DETAILED DESCRIPTION OF THE EMBODIMENT(S) OF THE INVENTION

The present disclosure will be described more fully with reference tothe accompanying drawings in which exemplary embodiments of the presentdisclosure are illustrated. However, it should be understood that thepresent disclosure may be embodied in a variety of different forms andshould not be construed as being limited to the embodiments set forthherein. Herein, the embodiments are provided to make the presentdisclosure more complete and thorough, and to fully convey the conceptof the present disclosure to those skilled in the art.

It should also be understood by those skilled in the art that the airconditioning system proposed by the present disclosure does not narrowlyrefer to an air conditioner for use in a building having an outdoorcooling/heating unit and an indoor heat exchange unit in the industry.It should be construed as a kind of thermal system with air conditioningfunction, which is driven by various types of power sources (forexample, electric power) to transfer the heat generated by phase changeof the refrigerant in the system to a position to be adjusted via thecoolant, and to exchange heat with the air there.

Referring to FIG. 1, an embodiment of an air conditioning system 100 isillustrated. The air conditioning system 100 includes a plurality ofindoor units 111, 112, a plurality of outdoor units 121, 122, and acoolant circulation circuit 130. The coolant circulation circuit 130 hasbranches connected in parallel with each other which lead to individualindoor units 111, 112 so that each branch exchanges heat with thecorresponding indoor units 111, 112 or is separately controlled.Similarly, the coolant circulation circuit 130 also has branchesconnected in parallel with each other which lead to the correspondingoutdoor units 121, 122 so that each branch exchanges heat with thecorresponding outdoor units 121, 122 or is separately controlled. Insuch an arrangement, each of the outdoor units 121, 122 typicallyincludes an independent refrigeration circuit such that the compressedrefrigerant in the refrigeration circuit transfers cold or heat betweenthe outdoor environment and the coolant in the coolant circuit 130. Thecoolant circuit transfers the cold or heat from the outdoor units 121,122 to the activated indoor units 111, 112 via the coolant. In thiscase, the indoor units 111 and 112 may have only a fan and an air outletstructure, thereby directly driving the air and the coolant circulationcircuit 130 passing through the indoor units 111 and 112 to exchangeheat via convection to realize the air conditioning function;alternatively, the indoor units 111, 112 may also have anotherrefrigeration circuit, that is, the air conditioning function isrealized by heat exchange between the coolant in the coolant circulationcircuit 130 and the application environment via the refrigerant in therefrigeration circuit again. Generally, in order to achieve control ofthe flow of the coolant in the coolant circulation circuit 130, ahydraulic module 131 is also provided, which typically includes a drivepump and a regulating valve to respectively realize the functions ofpower supplying and flow control.

In addition, the air conditioning system 100 further includes acontroller 140 which, based on an activation number of the indoor units111, 112, a total number of the indoor units 111, 112 and a total numberof the outdoor units 121, 122, defines an upper limit of an activationnumber of the outdoor units 121, 122, so that the flow rate of thecoolant flowing through the activated outdoor units 121, 122 is notlower than a preset flow rate. In this case, by associating theoperating state of the indoor units 111, 112 with the adjustment of theoutdoor units 121, 122, it is ensured that the outdoor units 121, 122will not be frozen due to overly low flow rate even if the indoor units111, 112 have a low load, and triggering of freezing alarm is alsoavoided.

In order to achieve the above control, as a specific manner ofdetermining, the upper limit of the activation number of the outdoorunits 121, 122 may be N_(limit)=K*(M_(running)/M_(total))*N_(total);where K is a set coefficient, M_(running) is the activation number ofthe indoor units 111, 112, M_(total) is the total number of the indoorunits 111, 112, and N_(total) is the total number the outdoor units 121,122. In this of case, if the activation number of the indoor units 111,112 has a reduced percentage in the total number of the indoor units111, 112, it means that the flow rate of the coolant in the coolantcirculation circuit 130 that is required to participate in work is alsoreduced accordingly; that is, the flow rate of the coolant flowingthrough each of the outdoor units 121, 122 is also reduced. In thissituation, in order to prevent the components in the outdoor units 121and 122 from being frozen due to the flow rate of the coolant flowingthrough the outdoor units 121 and 122 being lower than a preset flowrate, the activation number of the outdoor units 121 and 122 should bereduced. According to the above manner of determining, the number is theupper limit of the number of activatable outdoor units 121 and 122. Whenthe number of actually activated outdoor units 121 and 122 is not lessthan the upper limit, the flow rate of the coolant flowing through theoutdoor units 121 and 122 will be higher than the preset flow rate,which avoids the freezing problem and improves system reliability. Also,as can be known from the above manner of determining, the upper limit ofthe number is also associated with the set coefficient K, which is anoperating margin provided by the work staff. For example, K>1 can beset, for the purpose of improving reliability as much as possible, andK≤1 can be set, for the purpose of energy saving. In any case, it shouldbe ensured that the setting of K does not cause the following situationwithin the upper limit N_(limit) of the activation number of the outdoorunits 121, 122: the flow rate of the coolant flowing through the outdoorunits 121, 122 being lower than the preset flow rate. Therefore, K>1 istypically set. In a more reliable solution, K=2.5 is set.

Similarly, the preset flow rate mentioned in the foregoing embodimentmay be associated with various design parameters of the outdoor units121, 122, and the preset flow rate may be adjusted according to thedegree to which the freezing problem at a lower flow rate can betolerated. For example, in a more reliable solution, the preset flowrate can be set to be no less than 70% of the rated flow rate of theoutdoor units 121, 122.

In addition, when the above manner of determining is used in actualapplications to obtain the upper limit N_(limit) of the activationnumber of the outdoor units 121 and 122, there may be a case where theupper limit of the activation number is not an integer. However, thenumber of operable units in actual operation is necessarily an integer.In this case, when the obtained upper limit of the activation numberN_(limit)≤1, in order to ensure that the system can work normally,N_(limit) can be determined to be 1. When the obtained N_(limit)>1, theN_(limit) may be rounded down to ensure that the flow requirements ofthe activated outdoor units 121 and 122 are met. For example, whenN_(limit)=5.4, the upper limit of the activation number of the outdoorunits 121 and 122 is 5.

Furthermore, if it is desired to further improve the adjustmentcapability of the coolant circulation circuit 130 of the system, abypass branch 132 may be added in the circuit to provide a certaindegree of bypass flow to meet the minimum flow requirements of theoutdoor units 121, 122. Specifically, on one hand, it is necessary toensure that a coolant having a sufficient flow rate flows through theoutdoor units 121, 122 to prevent it from freezing; and on the otherhand, the cooling capacity or heating capacity required by the indoorunits 111, 112 is limited, and accordingly the flow rate of the coolantrequired to flow therethrough is also limited. In this case, if adifference between the coolant flow rate required by the outdoor unitsand the coolant flow rate required by the indoor units is within anadjustable range of the bypass branch 132, the bypass branch 132 isopened to bypass this part of coolant, so that the low load demand ofthe indoor units and the anti-freezing demand of the outdoor units areboth met.

Optionally, a temperature sensor may also be provided within the system.The temperature sensor is disposed downstream of the indoor units 111,112 in the coolant circulation circuit 130 to sense the temperature ofreturned water. In this case, the controller 140 is further configuredto, when the temperature of returned water is higher than a presettemperature, increase the activation number of the outdoor units 121,122 within the upper limit of the activation number of the outdoor units121, 122, and/or increase the operating frequency of the activatedoutdoor units 121, 122. At this point, on one hand, the output capacityof the outdoor units 121, 122 can be adjusted according to thetemperature of returned water, so that the cooling capacity or theheating capacity required by the indoor units 111, 112 can be met; andon the other hand, each of the above adjustments is within the upperlimit of the activation number of the outdoor units 121, 122, whereby itis ensured that the adjustment process does not affect the minimumoutput flow rate of the outdoor units 121, 122, thereby avoidingtriggering an alarm or occurrence of freezing phenomenon, and improvingsystem reliability.

Further, although not shown in the drawings, a control method of an airconditioning system is also provided herein. The control method can beapplied to the air conditioning system described in any of the foregoingembodiments or combinations thereof. Alternatively, it can be applied toother air conditioning systems as well. In this case, the airconditioning system to which the control method is applied shouldinclude: a plurality of indoor units connected in parallel; a pluralityof outdoor units connected in parallel; and a coolant circulationcircuit. The coolant circulation circuit flows through each of theindoor units connected in parallel and each of the outdoor unitsconnected in parallel respectively, and exchanges heat with each of theindoor units and each of the outdoor units. In addition, the airconditioning system should further include a controller. In theapplication process, the control method includes: based on an activationnumber of the indoor units, a total number of the indoor units and atotal number of the outdoor units, defining an upper limit of anactivation number of the outdoor units, so that the flow rate of thecoolant flowing through the activated outdoor units is not lower than apreset flow rate. Under the control of the control method, byassociating the operating state of the indoor units with the adjustmentof the outdoor units, it is ensured that the outdoor units will not befrozen due to overly low flow rate even if the indoor units have a lowload, and triggering of freezing alarm is also avoided.

In order to achieve the above control, as a specific manner ofdetermining in the control method, the upper limit of the activationnumber of the outdoor units may beN_(limit)=K*(M_(running)/M_(total))*N_(total); where K is a setcoefficient, M_(running) is the activation number of the indoor units,M_(total) is the total number of the indoor units, and N_(total) is thetotal number of the outdoor units. In this case, if the activationnumber of the indoor units has a reduced percentage in the total numberof the indoor units, it means that the flow rate of the coolant in thecoolant circulation circuit that is required to participate in work isalso reduced accordingly; that is, the flow rate of the coolant flowingthrough each of the outdoor units is also reduced. In this situation, inorder to prevent the components in the outdoor units from being frozendue to the flow rate of the coolant flowing through the outdoor unitsbeing lower than a preset flow rate, the activation number of theoutdoor units should be reduced. According to the above manner ofdetermining, the number is the upper limit of the number of activatableoutdoor units. When the number of actually activated outdoor units isnot less than the upper limit, the flow rate of the coolant flowingthrough the outdoor units will be higher than the preset flow rate,which avoids the freezing problem and improves system reliability. Also,as can be known from the above manner of determining, the upper limit ofthe number is also associated with the set coefficient K, which is anoperating margin provided by the work staff. For example, K>1 can beset, for the purpose of improving reliability as much as possible, andK≤1 can be set, for the purpose of energy saving. In any case, it shouldbe ensured that the setting of K does not cause the following situationwithin the upper limit N_(limit) of the activation number of the outdoorunits: the flow rate of the coolant flowing through the outdoor unitsbeing lower than the preset flow rate. Therefore, K>1 is typically set.In a more reliable solution, K=2.5 is set.

Similarly, the preset flow rate mentioned in the foregoing embodimentmay be associated with various design parameters of the outdoor units,and the preset flow rate may be adjusted according to the degree towhich the freezing problem at a lower flow rate can be tolerated. Forexample, in a more reliable solution, the preset flow rate can be set tobe no less than 70% of the rated flow rate of the outdoor units.

In addition, when the above manner of determining is used in actualapplications to obtain the upper limit N_(limit) of the activationnumber of the outdoor units, there may be a case where the upper limitof the activation number is not an integer. However, the number ofoperable units in actual operation is necessarily an integer. In thiscase, when the obtained upper limit of the activation numberN_(limit)≤1, in order to ensure that the system can work normally,N_(limit) can be determined to be 1. When the obtained N_(limit)>1, theN_(limit) may be rounded down to ensure that the flow requirements ofthe activated outdoor units are met. For example, when N_(limit)=5.4,the upper limit of the activation number of the outdoor units is 5.

Furthermore, if it is desired to further improve the adjustmentcapability of the coolant circulation circuit of the system, a bypassbranch may be added in the circuit to provide a certain degree of bypassflow to meet the minimum flow requirements of the outdoor units.

Optionally, a temperature sensor may also be provided within the systemto sense a temperature of returned water after the coolant in thecoolant circulation circuit flows out of the indoor units. In this case,the controller is further configured to adjust the outdoor units basedon the temperature of returned water. Specifically, the controller isconfigured to: when the temperature of returned water is higher than apreset temperature, increase the activation number of the outdoor unitswithin the upper limit of the activation number of the outdoor units,and/or increase the operating frequency of the activated outdoor units.At this point, on one hand, the output capacity of the outdoor units canbe adjusted according to the temperature of returned water, so that thecooling capacity or the heating capacity required by the indoor unitscan be met; and on the other hand, each of the above adjustments iswithin the upper limit of the activation number of the outdoor units,whereby it is ensured that the adjustment process does not affect theminimum output flow rate of the outdoor units, thereby avoidingtriggering an alarm or occurrence of freezing phenomenon, and improvingsystem reliability.

In addition, it should be noted that while particular order of steps mayhave been shown, disclosed, and claimed in the above particularembodiments, it is understood that some steps can be carried out,separated or combined in any order unless it is expressly indicated thatthey should be executed in the particular order.

The controllers described above for performing the aforementioned methodmay involve several functional entities that do not necessarily have tocorrespond to physically or logically independent entities. Thesefunctional entities may also be implemented in software, or implementedin one or more hardware modules or integrated circuits, or implementedin different processing devices and/or microcontroller devices.

In the description, examples are used to disclose the presentapplication, including the best mode, with the purpose of enabling anyperson skilled in the art to practice the application, including makingand using any device or system and performing any of the methodscovered. The scope of protection of the present application is definedby the claims, and may include other examples that can be conceived bythose skilled in the art. If such other examples have structuralelements that do not differ from the literal language of the claims, orif they include equivalent structural elements that do not substantivelydiffer from the literal language of the claims, these examples are alsointended to be included in the scope of the claims.

What is claimed is:
 1. An air conditioning system, characterized incomprising: a plurality of indoor units connected in parallel; aplurality of outdoor units connected in parallel; and a coolantcirculation circuit which flows through each of the indoor unitsconnected in parallel and each of the outdoor units connected inparallel respectively, and which exchanges heat with each of the indoorunits and each of the outdoor units; wherein the air conditioning systemfurther comprises a controller which, based on an activation number ofthe indoor units, a total number of the indoor units and a total numberof the outdoor units, defines an upper limit of an activation number ofthe outdoor units, so that the flow rate of the coolant flowing throughthe activated outdoor units is not lower than a preset flow rate.
 2. Theair conditioning system according to claim 1, wherein the upper limit ofthe activation number of the outdoor units isN_(limit)=K*(M_(running)/M_(total))*N_(total); where K is a setcoefficient, M_(running) is the activation number of the indoor units,M_(total) is the total number of the indoor units, and N_(total) is thetotal number of the outdoor units.
 3. The air conditioning systemaccording to claim 2, wherein when the obtained N_(limit)≤1, theN_(limit) is determined to be 1; and when the obtained N_(limit)>1, theN_(limit) is rounded down.
 4. The air conditioning system according toclaim 2, wherein K≤1 or K>1.
 5. The air conditioning system according toclaim 2, wherein K=2.5.
 6. The air conditioning system according toclaim 1, wherein the preset flow rate is not lower than 70% of a ratedflow rate of the outdoor units.
 7. The air conditioning system accordingto claim 1, further comprising a temperature sensor disposed downstreamof the indoor units in the coolant circulation circuit to sense atemperature of returned water; wherein the controller is furtherconfigured to, when the temperature of returned water is higher than apreset temperature, increase the activation number of the outdoor unitswithin the upper limit of the activation number of the outdoor units,and/or increase the operating frequency of the activated outdoor units.8. A control method of an air conditioning system, wherein the airconditioning system comprises: a plurality of indoor units connected inparallel; a plurality of outdoor units connected in parallel; a coolantcirculation circuit which flows through each of the indoor unitsconnected in parallel and each of the outdoor units connected inparallel respectively, and which exchanges heat with each of the indoorunits and each of the outdoor units; and a controller; the controlmethod comprises: based on an activation number of the indoor units, atotal number of the indoor units and a total number of the outdoorunits, defining an upper limit of an activation number of the outdoorunits, so that the flow rate of the coolant flowing through theactivated outdoor units is not lower than a preset flow rate.
 9. Thecontrol method according to claim 8, wherein the upper limit of theactivation number of the outdoor units isN_(limit)=K*(M_(running)/M_(total))*N_(total); where K is a setcoefficient, M_(running) is the activation number of the indoor units,M_(total) is the total number of the indoor units, and N_(total) is thetotal number of the outdoor units.
 10. The control method according toclaim 9, wherein when the obtained N_(limit)≤1, the N_(limit) isdetermined to be 1; and when the obtained N_(limit)>1, the N_(limit) isrounded down.
 11. The control method according to claim 9, wherein K≤1or K>1.
 12. The control method according to claim 9, wherein K=2.5. 13.The control method according to claim 8, wherein the preset flow rate isnot lower than 70% of a rated flow rate of the outdoor units.
 14. Thecontrol method according to claim 8, wherein a temperature of returnedwater after the coolant in the coolant circulation circuit flows out ofthe indoor units is obtained; when the temperature of returned water ishigher than a preset temperature, the activation number of the outdoorunits is increased within the upper limit of the activation number ofthe outdoor units, and/or the operating frequency of the activatedoutdoor units is increased.